Utilizing wood waste



n 7 1927. v 8 H. F. WEISS UTILIZING WOOD WASTE Original Filed May 19. 1921 mW QM m .m M W d 7% W Patented June 7, 1927.

UNITED s'rArEs PATENT or-rice.-

nowaan raannmox' wares, or nnraou, wrsoonsnr, erosion, a! mu AB- SIGNIENTS, TO WOOD CONVERSION CQIPANI,

PORATION OF DELAWARE.-

u'rlmzme woon was,

Original application filed lay 18, 1981, Serial Il'o'. 470,967. bidder! and this application fled I'ebrury I, ma. Serial an. 7,001.

There are now on the marketthree gengral types of wall board made from wood. a he wood is ground into a mechanical .pulp on grinding equipment such-as isused 1n making ordinary ground wood pulpforpaper manufacture. To this ground. wood pulp is added a certain amount of chemical pulp to give added strength to the finished product, then the mixture isfiowed over an ordi nary board machine into a sheet of paper having the thickness of ordinary card-board. At the end of the paper making machine the sheets are wound into rolls of a size convenient for transportation. The wall board is made from them'by un-rolling five rolls or more simultaneously and gluing or cementing the various sheets of paper together, usually with an adhesive such as sodium silicate. The sheets of paper or card-board thus glued together are then cut to the desired size and dried and in this form are commercial. wall board. Some manufacturers use waste papers invwhole or in part instead of ground round wood, but without change in the essentials of the Process as above outlined. Wall boards 0 this type are sold in the United States in greater tonnage than those of any'other type.

A second type of wall board now on the market is made by grinding the wood to a pulp and then beating the pulp in standard paper making heaters and finally flowing it into trays; these trays are then put into a hydraulic press and the mass is compressed into a dense product which is then removed from the press, dried, trimmed, and surfaced. Chemical pulp can be substituted in whole or in part for ground wood pulp in this type of board. This board consists of but one layer. and usually is denser and has a more compact surface than wall board made from paper sheets.

A third type of wall board is made by gluing or cementing between two heavy sheets of paper, slats of wood placed side by side. This board is expensive because of the cost of the wood slats and because of the relatively large quantity of sodium silicate or other adhesive that must be used in holding the slats together and in fastening the covering sheets firmly to the wood. The

first type is made as follows: Round.

covering sheets are relatively tough and 01' CLOQUET, MINNESOTA, A 003- thick and have the characteristic appear-.

anoe and surface texture of paper.

These three types include all of the various varieties 0 wood wall board 'now on the market in a large way. They all involve the step of first pre aring a wood'pul either mechanically or cl iemicall in stamf ard pulp making equipment. uch equipment 1s, from its very character, expensive to 1nstall and expensive to operate, and reguires-large floor area, particularly for the rlers of the paper making machine. Furthermore, the manufacture of all of these types starts with logs of good size and qualit? which, 1f not used in the manufacture 0 wall board, could well be used in the manufacture of newsprint aper and even more expensive pa ers. An aside from the standard pulp-ma ing equipment used in these processes, the boards themselves are made on large and expensive machines requ rmg large floor area; the single exception being the one ply board made on apress as above outlined.

All of the wall boards above described rely mainly for their strength upon the interlacing and interlocking of the fibers and, therefore, their processes of manufacture aim to make a. pu p having fibers as long as possible. In general, for best results, this requires the use of round wood of good quality and of grinding equipment well designed and carefully maintained. But around every saw mill there accumulates large quantities of what may be termed saw mill oflal or wood waste. such as slabs, edgings. trimmings, sawdust, shavings, and bark. Some of this material such as the slabs and edgings, is marketable, under favorable shipping conditions, to paper mills, but though the quality of fiber in the slabs and edgings is as good or better than the general run of fiber from round wood, the pieces of wood are in such physical condition that they are not readily reduced to a pulp. with the result that the yield of fiber is low. the quality of the pulp is poor, and

stone requires the expenditure largequantities of power.

For example, a ton of ground wood pulp, suitable for making the plies'of a wall board, requires 1200 to 2400 horsepower hours for grinding alone- This great quantity of power is consumed, partly in the mechanical work of tearing the fibers one from another, but more largely in frictional loss atthc surface of the stone where it rubs with heavy pressure on the log of wood and where the log acts as a brake on the stone.'"This frictional loss is dissipated in the form of heat and the heatfis carried away in the cooling water and thus is lost.

The coolim water, after separation of the fibers, is or 'narily run to waste.

- lit is anobject of the present invention that is dense and capable of taking a finish'and even a high polish, and i do 'can be ornamented by graining and paintto produce a wall board consisting essentially of a single ply, this board being free from sodium silicate, and being uniform throughout." The board may havea surface o sired,

ing methods now well developed in the decoration of sheet material, such for instance as sheet metahy 1 It is a further object of the present invention to produce a wall board of-acceptablecharacterom saw mill oiial such-as slabs, trimmings, edgings, sawdust, shavings,

and even bark and to do this with a power consumption far below that ordinarily I needed and in machinery and buildings less expensive than those now needed for the production of wall board from ground wood or from. chemical pulp. Other objects and advantages of the present invention will be come clear from the following description which is to be: taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a diagrammatic representation, in elevation, of a complete plant for making wall board by the present process, and Fig. 2 isa diagrammatic plan view ofthe same. The wall board of the present invention comprises a binder and a filler and the novelty in the. product lies particularly in the binder and in its combination with a filler of special character. There is also novelty in the process of making and using the binder, particularly for the manufac ture of a wall board such as that hereinafter described.

The binder consists essentially of lignocellulose gelatinized by mechanical disintegration preferably in the presence of water and without the use of any gelatiniz-'- ing chemical. This binder, when dry, 1s a hard, horny mass having good binding qualities,'and yet ofiering no impediment to usual woodworking operations, such he sawing, planing, chiseling, and the like. The binder is preferably made from sawdust or somewhat larger particles of raw. wood as assures by crushin or rolling the wood particles between re atively rotating discs whereby the fibers are torn apart and. subjected'to pressure in the presence of water, and ultlmately are converted substantially entirely into a.--gelatinized-mass. If wood particles other than sawdust are used as the raw material for the binder, they are preferably obtained by chipping,,hogging or shredding nnll'waste or ofial, and not by grinding solid wood on a stone as in pulp making.-

These chi s or "articles 'advantageolislyicain be waterogge to facilitate their mechanical disintegration and their. conversion into gelatinous material. i

The filler need not be separate fibers, as

excellent results are had by using bundles of fibers such as sawdust, preferably screened to'take out the finest and the coarsest particles. Incompletely gelatinized wood p'articles canconstitute the filler, and it is pos sible to use ground wood pulp or cooked wood pulp or old newspapers beaten to -a pulp as the filler but as hereinafter pointed out at length, there aremany' practical'EidQ vantages in usin sawdustor equivalent un ground and un eaten fibers grouped to'- gether or aggregated as in the living tree.

ill)

The details of the process and of the product in their preferred embodiments will be better understood from the following di's' closure. p j i i The binder.

Starting with saw mill ofi'al or waste, such as slabs, edgings, trimmings, shavings, and

even bark or with mixtures of these, or

starting with paper'mill offal orwaste such as crooked bolts, or limbs or branches such as are commonly left in the forest; either with or without preliminary removal of the bark by usual methods, as in thejso-called' drum barker, I pass the waste through a hog such as is used at sawmills for cutting up waste wood to make it suitable for fuel, or. througha chipper, such as is used in )reparing wood for the soda, sulfite or su] ate process, or through a coarse shredder, such as is sometimes used at saw mills in place of a hog to reduce wood to small chi s or fragments. If desired, a hog and a siredder may be used in conjunction, the hog cutting the wood into fra ments say two inches long, and the shredder beating these fragments into smaller pieces. Good mill 0 1,681,178 8. ground 'ulp. Also, the product .reanother procedure, the small wood parsulting from (11 y ,difierent ticles while hot from the exposure tohot 4 'p ing is entire from ground wood'pulp Thus by chipping, the saw mill or paper fi al is reduced to a mass of chi s 'or wood particles of asize about one-ha] inch in length by one-eighth inch in diameter, or less.'- This material is then passed over a series of screens and the very' fine particles, which for want of a better nameI will hereinafter designate as fiber ag reates, are collected and stored in a in. hese fiber aggregates may be-as fine as 9rdinary sawdust and in fact by starting with sawdust, such as is obtainable at any saw milll can dispense with the chipping procedure described above, for the material is already fine enough to be called fiber agregates and to be used as such. .In the c lrawing, the bin for holding'the sawdust or other. fiber aggregates is marked with reference character 1. p

The next coarser grade from the screens,

V which I prefer'to call small wood partithe screen to the cles, goes ultimately to a storage bin 2, and the coarsest particles are returned from saliredder for retreatment and ultimate conv rsion into small wood particles and intol the smaller fibera gregates. If thesaw mill waste is all In the form of sawdust, or otherlike small particles, the chipping and shredding steps can be omitted for the material that is to go into bin 2, the same -as for that supplied to bin 1. f

The small wood particles that are to be supplied tob in 2 can with advantage be iven a wa ter-logging treatment after hemg taken 'from the screen and before be 'ing delivered into the bin.

to be used as a raw material, the procedure is the same.

1f sawdust is This water-logging is used because wood that is wet is very much weaker and can be torn apart with less expenditure of energy than wood that is dryt.he 'fibers separate from one another moreeasily. For example, wet wood has. in compression, about one-half to one-third of the strength of dry wood. This waterlogging can be done conveniently by tirst submerging the small wood particles in water heated near or preferably to the boiling point, and then, while the wood particles are submerged in a closed tank, subjecting the mass to pressure such as steam pressure to force the hot water into the fiber aggregates.

As an alternative procedure. the small woodparticles can be thoroughly heated in the hot water and then. while the temperature of the water is near or at the boiling point, cold water can be added to cause con-- traction of the expanded air and gases of the wood particles, thereby drawing water into the pores or voids of the particles.

submerged in water it woul -Nos. 565,690. issued Aug. 1], 817.610. issued Apr. 10. 1906. In

water, can be dum ed into cold water to cause contraction o the expanded air and gases as above described. Under some circumstances, it is more economical merely to let. the hot water and the sulunerged wood particles cool by radiation, for by so doing large quantities of water will be drawn into the res and voids of the'wood. V

B suc i a treatment, small wood articles (and sawdust) can be so tho'rou h y saturated with water thatthey ii iil sink in waterin an hour or less. Ifthevwcre merely take months and, in the case of resistant woods, years, before the wood soaked up enough water to sink. The heating in hot water is not intended to be a cooking operation and there need be no chemical present to effect cooking. Neverthelcss, the hot water dissolves out some or perhaps allot the highly sol u ble constituents of the wood. When western larch is used as the wood, this is a valuable featured the process, because of-the possibilit-yv of recovering valuable sugar-making ingredients from the liquor.

The small wood particles (which, as above explained, may be nothing more than sawdustor may be larger particles), now thoroughly saturated with water and consequentlyin a very weak condition, are' passed into. hopper 2 (Fig. 1) preparatory to delivery into a machine 3 whereby they are torn apart and reduced to separated fibers. Since \ToOTl is weaker hotthan cold, I refer to pass the small wood particles into t iis machine while they are still hot from the water-logging rocc'dure. If the chilling with cold water as completely cooled the wood particles, it is sometimes advisable to again heat them up before delivery into machine 3. The machine 3, for separating the-fibers, may be constructed in many ways,hut best results have been obtained by me in an apparatus having two large discs of metal, one of which is rotatable with respect to the other. and between which the hot and water-logged wood is subjected to a rolling action to tear, ormore strictly speaking, crush the fibers one from another. Good results have been obtained by use of disc grinders common- 1y known as corn crackers. The details of such a disc grinder or corn cracker are well illustrated. in U, S. Letters Patent .1896, and such a machine, the action of tearing the wood fibers apart resembles somewhat the disintegrating effect of rolling a match under foot on the floor, excepting, however, that because of therelat-ive rotative movement of the discs, each piece of wood or bundle of fibers has a gyroscopic motion about the axis of the rotating disc so that not only are the fibers and bundles of fibers subjected to a crushing action, but they are subjected to a twisting effeet. As one disc rotates with res ect to the other, the small wood particles or hundles of fibers will naturally take up positions along radii of the rotating disc, andrsince their outer ends travel through a greater distance than their inner ends, there will be a decided tendency for the fibers to slip longitudinally with a twisting movement. That is to say, there is not only a crushing pressure er enrolled have slightly concaved faces and can rotatable.

be roughened or surfaced to accelerate the disintegrating action or fiber liberation. Both plates may rotate in opposite directions, or one may be stationary and the other The working faces of the discs are preferably of metal: but of whatever material,-the surfaces are adjusted in such manner that they do not touch. It is also important that means be provided for adjusting the distance between the plates in accordance with the size, character and origin of the wood particles under treatment, and the character of the product desired. It is a rolling and twisting action rather than a grinding action that gives best results in the manufacture of the products hereinafter described. Too much of the grinding action produces too large a percentage of wood flour, as distinguished from fiber pulp.

The powerconsumed for reducing wood to pulp by first chipping, then shredding and then rolling the small wood particles-between two relativel moving discs as above described, is much less than that required for tearing the fibers apart on an ordinary paper mill grindstone; for not only has the 0111pping and shredding cut the fibers from the solid wood, but the resistance or strength of the particles has been reduced by waterlogging and by heating, and, furthermore, the disintegrating or fiber-liberating power is applied to the particles in compression and in shear, and therefore along their lines of least resistance. Also, in this process, friction and frictional losses have been reduced to a minimum. The bundles of fibers act as rollers between the moving surfacest eatre product because of too great breakage of individual fibers and too high a roduction of wood flour. The material de ivered t'rom machine3 can be screened and the wood particles of proper size to be called fiber aggre gates can be separatedout and delivered to bin l'as a substitute for, or an admixture to, the sawdust therein. I To reduce the wood to individual fibers, it may be passed repeatedly through the same fiber liberating machine, screens being used to separate out those fibers that have been sufiiciently reduced and returning to the machine for further treatmentonly the coarser bundles or shives. Or, if desired, a series of fiber liberating machines may be used in each succeeding one or which the relatively, moving surfaces are so adjusted as to give best disintegrating action on the partially reduced wood with which it'is supplied. The latter procedure is preferable.

Such an arrangement is indicated diagrammati'cally in Fi 2 of the drawings, where the material de ivered from disc grinder 3 is carried by an elevator 4 to a hopper 5 adapted to deliver to a disc grinder 6. When delivered from the latter to tank 7, the mass can be lifted by pump 8 and delivered through pipes 9 or 10 to grinders llor 12, which, in turn, deliver to tank 13 from which the mass can similarly be pumped to other disc grinders of the series. As the wood proceeds through the series of grinders, the particles are torn apart into separate individual fibers and furthermore these fibers undergo a chemical change and ultimately are delivered from the last grinder of the series into storage tank 14 as a gelatinous, structureless mass free from chemicals of any sort and well adapted for use as a binder in the wall board of m present invention.

It is well recognize 1n the literature that. the hydration qualities of lignocellulose orwood are not very great, and that mechanical wood pulp suffers little alteration by heat-- ing in a paper-makers beater. But I have found that when lignocellulose or wood is crushed or rolled under ressure in a corn cracker, hydration will egin even in the first mill of the series, and the hydration will progressively increase as the wood is reduced to fiber and the fibers are broken and crumbled under pressure. The water-logging treatment to which the wood has been.

subjected facilitates hydration. Furthermore, the wood hydrates and approaches gelatinization more easily while it is warm or hot. However, it is entirely possible to produce gelatinized lignocellulose without giving it the water-logging treatment and by ound, but I also there is apt to be a bad e ect on the rolling and breaking the fibers in cold water instead of hot.

While the hydration or gelatinizing effect may not be very great in grinder 3 (Fig. 2), the ,other, and particularlythe last grinders of the series, in which the plates are set close together, so completely comb out, crush and gelatinize the wood fibers, that their fibrous structure disappears entirely.

The resultant roduct is a slimy gelatinous mass of lignocel ulose. This might perhaps be called hydrated lignocellulose, thou h I know of no method for, determining ow manylwater molecules have attached themselves to the cellulose molecule or if indeed any such water molecules have been added. I know that the chemical structure must be different from that of lignocellulose, and as appears below, the. physical structure is likewise radically difierent. Therefore, for lack of a better name, I have hereindesignated this material, which is to be the binder or binding element of the wall board, as ge-' latinized lignocellulose. Gelatinized lignocellulose, as the term is herein used, means wood fibers (lignocellulose) that have been so treated mechanically as to be completely torn and broken so that their length is but a fractional part of their original length, say for instance, onetenth or less; furthermore, the original wood cellulose has been changed chemically, though only by mechanical treatment in the presence of water, and perhaps to the extent of addingto it an unknown number of Water molecules. The material, when wet, is a slime which on drying shrinks enormously and is inclined to warp and forms a dense hard bone-like mass of considerable strength and without appreciable fibrous structure, but inclined to split or flake, and ofa color usually somewhat darker than that of thewood from which it was made. Made from pine, spruce, or hemlock, the material is cream colored", and made from fir, tamaraek or larch, it is somewhat darker in color. It can be made readi ly from any of these woods, and others, but with cedar the problem is more diflicult because of diificulties in chemically changing the water-resistant fibers of such a gymnosperm. To gelatinize water-resistant fibers, such as cedar, I find it expedient to supply the grinders, not with water, but with an aqueous solution of sodiumsilicate. This is not so cheap as water alone and yields a final product that may not be entirely free from chemical additions, and therefore more likely 'to change in color, or otherwise, while in use as on the wall of a building.

WVhen properly made, the gelatinized lignocellulose contains no spindle. sha ed fibers of their original length, nor bund es of cut fibers, such. as is found in wood flour. Both physically and chemically, gelatinized lignocellulose is readily distinguis able from wood flour, though according to my experiments, wood flour often results from rolonged mechanical treatments of wood fie]? as for instance, when the fiber is pass repeatedly through a Jordan.

This gelatinized lignocellulose is one of the materials used by me in the production of wall board, and not only constitutes an appreciable percentage of the total material used, but acts as a binder to unite with and hold in place the other and more inert material or materials hereinafter designated as the filler.

A feature which readily may be incorporated in the above described process of making gelatinized lignocellulose is the recirculation of the water insome, at least, of the fiber-liberating machines which, with the soluble material inthe wood, can be recovered in a manner similar to that described in my U. S. Patent No. 1,339,489, issued May 11, 1920. Furthermore, whenever a plurality of fiber liberating machines are used in series to progressively reduce the wood particles to pulp, and then to gelatinize the pulp, the circulation of the water to take out soluble material (as from western larch), can be on the counter-current principle, that 18 to say, the water used in the last machine or grinder of the series can be filtered oil from the pulpy material delivered therefrom and can be introduced as the flushing water of the machine next preceding, and so on throughout the series, the strongest solution of soluble constituents being drawn 01f from the partially disintegrated shredded wood particles of the machine into, which these Stored in bin 1 is the filler for the board. As above explained, this material may be sawdust or may be the finer particles obtained by screening material from the shredder, or'may have been obtained by screening the material delivered from one of the grinders. I have called these smallest wood particles liber aggregates, and by fiber aggregates I mean five or more wood fibers still joined together as in the living tree. The fibers need not, however, be of full length, and in the case of sawdust, often are not. Shingle sawdust is very good raw material for use as a filler after the very fine and the very coarse particles have been screened'out. This sawdust is slivery in character, light in weight, and durable, and has the further characteristic, particularly if made from cedar, that it does not hydrate during mixing nor while in use.

Instead of using a dry filler, such as sawdust, the filler may be obtained from other sources. For instance, it may consist of a part of the output of one or more of the grinders or gelatinizers above described, or

coarse particles screened from the output of one or more of those gelatinizers, and may Such a material blends well with the completely gelatinized and structureless binder and of course is cheap, for it can be made of saw mill offal with the expenditure of but little power.

But instead of 11811151 fiber aggregates in whole or in part, as ahove described, I can 7 use a more expensive filler, such as ground i the incompletely wood pulp, or cooked .wood pulp, or mixtures of these; or I can beat up newspapers and other paper waste in a heater and. use the resultant pulp, but none of these substitute fillers is as satisfactory for my purpose as fiber aggre ates, such as sawdust or isintegrated product of one of the early grinders of the series, and none of them gives a wall board that is as easy to dry, is as free from shrinkage, has as beautiful a surface, nor is as good a sound and heat insulator, as when fiber aggregates are used as the filler of the board.

The miming.

The next step in the production of the wallthe gelatinized' board consists in mixing lignocellulose with the filler. The latter, as above explained, may consist wholly, or in large art, of wood fiber aggregates of the same origin as that which went into the galatinizers. Or the filler may be a different wood, as for instance, one noteasily gelatinized by grinding in water, such as cedar or aspen. To bringthe gelatinized lignocellulose and the wood fiber aggregates into intimate contact and to insure a mass uniform throughout, I pump the slimy'gelatinized lignocellulose into a mechanical mixer 15,consisting of a metal trough, set at a slight incline,

and provided with a power driven stirrer, comprising a central shaft on which are mounted a series of inclined stirring blades or paddles. The fiber aggregates are fed to this from hopper 1, and water may be added L 2) like those in ordinary paper making machines and so constructed as to. maintain a to thin the mix.

The relative roportions of the several ingredients of t e mixture may be varied through relativelywide limits. Up to a oer-I tain point, the larger the percentage of gelatinized lignocellulose, the stronger is the resultant board. The board should contain 25% or more by dry wood weight of the gelatinized lignocellulose and 30% or more by dry wood wei ht of fiber aggregates. A mixture com osed of gelatinizedlignocellulose an 40% fiber aggregates, by dry wood weight, to which enough water has hind of wood, and even of the same' been added to make the how readily,

gives a very strong, stifi and satisfactory. wall board. Cedar sawdust is satisfactory as a filler, though not readily adapted to the manufacture of the binder. S ruce or pine give astronger board than ce ar vert the soluble sodium resinate into an insoluble resinate, all in conformity with standard practice for sizing and Waterproofing paper. This treatment sizes the fiber aggregates and makes them and the finished board highly resistant to moisture. These materials may be omitted entirely when water-proofing is not desired, without impairing the strength or other characteristics of the board excepting that of its resistance to water. Normally,the-percentage of sodium resinate ma be from two to eight per cent of the dry welghts of the other components, depending on the kind of wood used and particularly its resinous content, and the degree of waterproofing desired in the finished product. The O((i uantity of alum is in proportion to the s ium resinate, due allowance being made for the amount of water resent, etc.

I a fire-proof board is desired, the requisite amount of ammonium sulfate can be added tothe batch while in the 'mixer. A non-mineral coloring, such as an aniline dye, can also be added, if a colored board is desired. .This is particularly advantageous ace when the board is to be finished in imitation of mahogany.

Another treatment consists in colorin the gelatinized lignocellulose one color an the filler a diflerent shade or color.

a very 'pleasing product.

I v I Pressing. v The now thoroughly mixed mass of gelatinized lignocellulose and sized fiber aggregates is next delivered to a flow box 17 (Fig.

constant head in the box with an overflow into an underground storage tank 18 (Fig.

This gives iis manna 22 and 23 and is reinforced along its upper stretch by underlying and power driven endless traveling screens 24 and 25 suitably supported on drums and rollers. This prevents sagging of the canvas belt while its load of material is being delivered to and from the press. To make a board about thick, the thickness of this layer as it flows onto the canvas belt is approximately 2% inches.

The width of the canvas belt corresponds with the length of the board or panel to be made, and the cellulosic mass is prevented from flowing oif the sides of the belt by means of two stationary baflies 26 and 27 (Fi 2). These baffles are adjustable lateral y to accommodate various widths of cellulosic mass, to accord with changes in the length of the boards to be made. In general, a board length of sixteen feet is suitable for ordinary trade demands. Thus the cellulosic mass in a relativel thick and uniform layer sixteen feet wi e and one inch thick on the canvas belt is carried forward between the stationary side barriers 26 and 27 and ultimately passes between the platens of a hydraulic press. The canvas belt moves forward with an intermittent movement and as soonas the proper amount of the mass is between, the platens, a rectangular die 28 having inside dimensions corresponding to the size of the board to be made, is lowered into the mass until it rests on the canvas sheet. The cellulosic mass is so fluid that it readily moves aside to permit this lowering of the die. Then the upper platen, which fits within the die with a substantially water tight joint, is lowered into the die and compresses the cellulosic mass, while simultaneously squeezing its excess water both upward and downward through suitable slots in the platens. The platens then separate, the die lifts, and the belt moves forward until a fresh amount of material has passed between the platens, when the operation just described is repeated. This entire operation is done mechanically andless time than a minute is needed to press each sheet.

In order to prevent that part of the cellulosic mass which has not been pressed from flowing onto the compressed mass after the platens have been released there are provided a series of cross baflles or partitions 31, adjustably attached between two sprocket chains 32 which are driven by a power driven sprocket 33 and pass over guide wheels 34, 35 and 36 as shown. These baffles or partitions, which may be made wood, press down into the soft watery mass before it reaches the press and block it off into rectangles of approximatelythe size needed at the press. Because of these cross baffles 31 and the side barriers 26 and 27 there is no necessity for usin trays in which to form and press the boar s.

By changing the distance between the cross baflles 31, the width of the board can be varied in the same way that its length can be varied by changing the distance between the side barriers 26 and 27.

Drying.

uniform drying action and to lessen such I tendency as there may be for warpage of the boards. The dry kiln removes the water from the boards so that they emergefrom the kiln, dry, stiff and hard. r

v Finishing.

The boards are next run through saws and are'marketa ble in place of wall board made by usual processes. The boards may be nailed directly to the studding of a building to serve in place of lath and plaster, and like wall board now on the market, may be sawed and similarly cut to meet the needs of the builder. But unlike wall boards of more usual manufacture, they contain no sodium silicate or other mineral harmful to the saws and other edge tools of the carpenter. On thev contrary, they consist throughout of nothing but woody material through which a sawor chisel will work as readily as through solid wood and with no more injury to the edge of the tool. The rosin size and the ammonium sulfate, if present, arenot harmful to the edge tools. But in many respects this new product is different from wall board made from paper sheets cemented together, for, if desired, the wall board of the present invention may be passed through an ordinary wood planer to finish the surface, or through a sand ma chine to dress its surface, or between steel rolls to give the surface either a high polish or to impress in or on the surface patterns or designs or to give a finish similar to burlap or canvas. Likewise, the finished and even polished face of the board may be treated much as I sheet steel is now treated to give it the appearance of grained mahogany or other woods. The surface can be painted and decorated much as can be done with solid wood. excepting that it has not the characteristic grain of.

wood, but on the contrary, if made with fiber cut to desired size or shape and in that form mottled appearance not unlike the so-called oatmeal wall papers. 1

As above indicated, the process by which this novel and valuable product is made, may vary in many of its details, both as to the origin of, the raw materials and as to the procedure bywhich those materials are treated to bring them into proper hysical and chemical condition tounite un er pressure and kiln drying into the product described in detail above. It is of particular importance, however, that no chemical need be used in the process and that wateralone, togetherwith suitable mechanical manipulations, such as cutting, rolling, and twisting, properly repeated, is-suflicient to convert saw mill oflal such as slabs, edgings, trimmings, sawdust, shavings, and even bark, into a readily marketable product and with relatively low power consumption.

As a permissible variation from the preferred method above described, I may proceed by chipping saw mill offal such as slabs, edgings, trimmings, shavings, or bark, or paper makers waste, such as crooked bolts, saplings, and the limbs and branches ordinarily left in the forest, and then nechani- 'cally disintegrating the chipped wood by grinding or, more strictly speaking, crushmg, in a disc grinder in the presence of water, preferably hot water, as above described, and with or without the preliminary water-logging. and stopping this mechanical disintegration before the fiber aggregates are completely reduced to a structureless gelatinized mass. For instance, I can carry the wood throughless than six grindings and obtain a mixture consisting in part, say 60%, of completely gelatinized material and in part, say 40%, of wood fibers and fiber aggregates which have been gelatinized on the surface but are of woody character at the core. The exact number of grindingsrequisite for the desired result depends on many factors, such as the character of the wood and whether it is highly resistant to water, whether it has been water-logged before grinding, how close together the grinding plates have been set and whether hot water has been used in the grinders,-etc. But roughly stated, three or four water grindings as above described willyield a product approximately half of which is in' a gelatinized condition, andthe other half of which consists of fibers and fiber aggregates with buta surface gelatinization. mixture, when delivered from the grinders, can be pumped into mixer. 15 and thereafter can be sized. fireproofcd, and then flowed out in a sheet for pressing, drying and finishing in much the same way as if sawdust or equivalent dry fiber aggregates were used as afiller with a completely gelatinized binder. This alternative procedure, though permissible, is in my present opinion not so good Such a enemas as that first described, and yields a product having the disadvantages that it is not so cheap, not so attractive,'not so good as a heat or sound insulator (because of the relative absence of voids and air pockets), more inclined to shrink and warp on drying, not so easy to dry, and not so light in weight. Also, a board so made has a monotonous appearance quite in contrast with the beautiful mottled or composite appearance resulting from the use of fiber aggregates that have not been broken up by passage through a disc grinder.

As a still further permissible variation, an incompletely gelatinized mass of fiber a gregates mechanically disintegrated by grinding or crushing in the presence of water, as above described, can be used as a binder for a filler consisting essentially of unground fiber aggregates such as a sawdust, due care being taken to keep the proportion of binder to filler within the ranges dictated by the requirements of strength, freedom from warping, undue shrinkage and the like. I

Preferably, the mass as it reaches the press, should comprise at least 25% by dry 'wood weight of. mechanically gelatinized lignocellulose, and preferably as much as 40% to 60%. Likewise, the mass should contain. as much as 30% or more by dry weight of fiber aggregates and preferably as much as 60% to 40%.

The apparatus whereby the process is cari ried out obviously may vary in details without fundamentally altering either the process or the product c aimed herein. Novel features of the apparatus will be claimed in a.

separate application.

This application is a'dlvisi'on ofmy copending application, Serial Number 470,967,

'ly disintegrating wood in hot water until at least 25% of the fibers have been crushed and broken andconverted into a structure'- less gelatinous mass.

3. The method of preparing a wall board binder which comprises chipping mill waste, reducing the chips to small wood particles, and mechanically disintegrating the parti. cles in water until at least 25% of the fibers have been crushed and broken and converted into a structureless gelatinous mass.

4. The method of preparing gelatinous. lignocellulose which consists in water-logging the wood and then mechanically disintegratin the wet wood by crushing and rolling tween relatively rotating discs, substantially as described.

5. The method of preparing gelatinous lignocellulose which consists in water-logging the wood and then mechanically disintegrating the wood in water until a substantial part of it has been reduced to a structure ess gelatinous mass substantially 19 as described.

6. The method of makinga wall board centage of the wood has been reduce binder which consists in chipping saw oil'al, reducingv the chips to small wood par-'- ticles, water-lo ing and rolling the particles between rela-' ti'vely rotating discs until a substantial rto a structureless gelatinous mass, substantially as described. 7

In testimony whereof I aflix my signature.

HOWARD FREDERICK 'wmss.

gging the particles, and crush-' 

